Direct clean-up and analysis of ribonucleosides in physiological fluids.

We describe the group-selective separation and quantification of unmodified, modified and hypermodified ribonucleosides in physiological fluids (urine, serum) by on-line multidimensional high-performance affinity chromatography (HPAC)-reversed-phase liquid chromatography (RPLC). The excretion levels and patterns of ribonucleosides such as N1-methyladenosine, N1-methylinosine, N2-methylguanosine, N2-dimethylguanosine, N6-carbamoylthreonyladenosine and 2-pyridone-5-carboxamido-N-ribofuranoside were determined in urines from a control group and from patients with different diseases. The HPAC-RPLC method applied represents a powerful tool, e.g. as a non-invasive screening test, a method to investigate disorders in ribonucleoside and/or RNA metabolism, a method for drug monitoring during nucleoside chemotherapy, and a method to study renal ribonucleoside reutilization.

[Antibody diversity and network theory--a hypothesis]. / Antikörpervielfalt und Netzwerktheorie--eine Hypothese.

The diversity of antibody specificities arises during the development of the immune system by recombination of genes and by spontaneous mutations and is not yet determined in the germ-cell, as earlier supposed. The network theory describes how antibody and lymphocyte populations are regulated recognizing each other by idiotopes. It is proposed that protection against autoaggression by an immune system with a genetically mostly uncontrolled high variability of specificities is based on anti-idiotypic antibodies which express autoantigen structures. There are suggestions that essential functions of the immune system consist not only in protection against microbes and immunological surveillance but also in regulatory effects on nonimmunological body-cell systems.

[ELISA detection of protamine antibodies]. / ELISA-Nachweis von Protaminantikörpern.

Protamine is frequently used as an adjuvant in insulin preparations. As alien protein protamine is immunogenic. We developed an ELISA for detection of protamine antibodies. As a strongly basic molecule protamine shows remarkable reactivity. Resulting methodical difficulties with regard to the assay are discussed. The course of antibody titres to protamine after immunization is shown in rabbits, goats, sheep and guinea pigs with positive results in all species. In humans protamine antibodies were detectable in 4% of 150 patients treated with protamine insulins.

Laser nephelometric equivalence point titration for the measurements of specific proteins in turbid biological fluids.

A reliable, sensitive and specific laser nephelometric (LN) assay for the quantitative measurement of specific proteins in body fluids by equivalence point titration is described. The method is relatively free from interference encountered in conventional LN assays, e.g. unspecific background scatter, antigen excess, and the inhibition of complex formation by high ionic strength and salt concentration, low pH and elevated urea concentrations. It can be applied to turbid body fluids containing relatively small amounts of antigen. A serial dilution of the antigen preparation (human urinary albumin in the present work) is incubated with a fixed amount of highly diluted specific antiserum. The antigen concentration is determined by estimation of the equivalence point on the LN immunoprecipitation curve and comparison of this position with that on a standard curve. The data presented show good correlation with values obtained by radioimmunoassay (p less than or equal to 1 X 10(-5);log (LNET) = 0.956 log (RIA) - 0.03; n = 50).

[The antisera avidity]. / Untersuchungen zur Avidität von Antiseren.

In a LN-equivalence point titration system the modulation of immune complex formation of high avide antisera by specific and unspecific factors is measurable. Protamine-Cl is a potent enhancer of complex formation.